The present disclosure relates to a sheet feeding device configured to feed a sheet and an image forming apparatus including the sheet feeding device.
In an image forming apparatus such as a copying machine or a printer, a sheet is fed from a sheet feeding cassette by a sheet feeding device to an image forming part. The sheet feeding device is provided with a pickup roller, a feed roller and a retard roller. The pickup roller feeds the sheet from the sheet feeding cassette. The feed roller conveys the fed sheet to the image forming part. The retard roller conveys the sheet one by one without double feeding.
These rollers come into contact with the sheet and thus are worn away by friction with the sheet in a long time use. Alternatively, paper powder is easily adhered on these rollers depending on a type of sheet. This deteriorates a conveying force of the sheet and thus a feeding failure is likely to occur. Accordingly, it is preferable for these rollers to be easily replaced and repaired.
Then, there is a sheet feeding device in which a feed holder which supports the pickup roller and the feed roller is attachable to and detachable from an apparatus main body while the retard roller is disposed on the apparatus main body. When the feed holder is mounted to the apparatus main body, the feed roller is coupled to a driving shaft disposed on the apparatus main body. The feed roller is driven by the rotating force of the driving shaft to be rotated and the pickup roller is also rotated by the rotating force transmitted from the feed roller. The sheet feeding device makes it easy to replace the rollers by dismounting the feed holder from the apparatus main body.
In addition, in order to position the feed holder to the apparatus main body, a guide shaft protruding on the same axis of the pickup roller is formed on the feed holder while a guide groove with which the guide shaft is engaged and guided into a predetermined feeding position is formed on the apparatus main body.
As described above, in a case where the guide shaft protruding on the same axis of the pickup roller is formed on the feed holder, because a protrusion length of the guide shaft is long, some problems may occur. For example, a dye used for molding the feed holder requires a deep cavity. Alternatively, a degree of freedom in design of the dye becomes low.
In addition, when the image forming apparatus may have a rear face C-path route formed along a rear face of the apparatus main body in a substantial C-shape, the feed holder is mounted and dismounted from the rear side of the apparatus main body. Furthermore, in some image forming apparatuses, a manual bypass path may be formed from a front side of the apparatus main body toward the rear side above the sheet feeding cassette. The manual bypass path is joined to a main conveying path on a downstream side of the sheet feeding device,
In the image forming apparatus having the above conveying paths, when the feed holder is mounted from the rear side of the apparatus main body, if the guide shaft protrudes on the same axis on the pickup roller, it is necessary to engage the guide shaft with the guide groove while avoiding the driving shaft of the feed roller. This complicates the mounting work. In addition, it is necessary to keep a passing space through which an upper portion above the guide shaft of the feed roller is passed. When a reduction in size of the image forming apparatus advances, the passing space may interfere with the manual bypass path.
Alternatively, in order to position the feed holder to the apparatus main body without forming the guide shaft and the guide groove, a positioning member is required for each of the feed holder and the apparatus main body. This leads to complication in structure of the sheet feeding device and increasing in cost.